In BasicPortAllocator test, don't require a specific candidate order.
In BasicPortAllocator test, don't require a specific candidate order.

The test doesn't really care about the order; the fact that it relied
on a specific order was just an implementation detail.

However, this made the test flaky since race conditions sometimes
determine the order. It also made it frustrating to add new tests.

BUG=webrtc:5930
R=pthatcher@webrtc.org

Review URL: https://codereview.webrtc.org/2006263004 .

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#12936}

TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc